RulesEncoding emits shortest-form msgpack (fixint/fixstr/fixmap first, float64 for floats). Decoding covers every type: bin becomes Base64, the timestamp extension becomes ISO time, other ext types become tagged strings, and (u)int64 beyond the safe range becomes a string — each with a counter.

JSON

Load some data to start

MessagePackHex

Load data and the result will appear here

Smaller and faster than JSON

JSON to MessagePack Converter

Two-way encode / decode · Hex & Base64 · timestamp ext support · runs locally

🔒Data is processed locally in your browser — never uploaded or stored

No upload, no storage

JSON is processed in memory and never sent to a server.

Share via URL fragment

Share links encode data in the # anchor — never sent to a server.

Remember last edit

Optionally keep your last input locally; clear it with one click.

Why use this JSON to MessagePack converter

Debug binary messages

msgpack payloads from Redis caches, RPC frames and game protocols — paste the Hex or Base64 and get readable JSON instantly.

Two-way conversion

Encode JSON to msgpack to compare sizes or craft test frames; decode msgpack back to JSON to inspect fields — one page, both directions.

Every type supported

bin, ext, timestamps (32/64/96-bit), float32/64 and (u)int64 big integers are all handled, each conversion counted and reported.

Precise error positions

Truncated data, the reserved 0xc1 byte and trailing bytes all report an exact byte offset — not a vague parse error.

Local & private

Cache and protocol payloads carry business data — everything is encoded and decoded on your machine, nothing uploaded.